The treatment container in dishwashers is usually made of stainless steel. The treatment container frequently consists of at least two components. The so-called container case forms the side walls and the top of a container hood of the treatment container and is connected for example with a separately formed rear wall which is likewise a constituent part of the container hood. This assembly is then connected with a dishwasher tub. For reasons of corrosion resistance the components of the treatment container are made of high-quality chromium-nickel (Cr—Ni) steel, which is relatively expensive. The use of chromium-nickel steel ensures that corrosion resistance is guaranteed also in areas where there is a mechanical connection between the container case and the rear wall, which usually takes the form of a weld seam.
From the production point of view it would be preferable if significant parts of the treatment container could be made of the simpler chromium (Cr) steel because this would reduce the costs of manufacture. The problem that exists with connecting chromium steel with chromium-nickel steel by welding is that crevice corrosion can arise in the area of the weld in water-conducting household appliances such as dishwashers. Crevice corrosion can also arise if the entire container hood is made of a chromium-steel assembly.
To avoid crevice corrosion special connection technologies are therefore needed to join together the two components of the treatment container of the water-conducting household appliance.
From FR 2 396 603 a treatment container is known for a dishwasher in which the container top and the container bottom tub are in each case connected with the side walls by means of a fold with an inserted seal. The sealing effect, i.e. the sealing of a gap between the two components, is achieved by a squeezing action. It is questionable here whether the seal element can be pressed in the direction of the interior of the treatment container as shown in the figures. It is further questionable whether the seal element in the way shown in the figures is not squeezed out by the squeezing action where the components meet. It is further doubtful whether the seal element on the side facing the interior of the dishwasher fits intimately on the component walls so that the desired seal is actually achieved.
From U.S. Pat. No. 3,545,147 and U.S. Pat. No. 3,213,583 connection technologies are known for caravan roofs. In FIG. 7 the connection technology is shown in more detail, showing the mechanical connection produced using a separate holding element which exhibits an independent mechanical connection with the edge sections of the components to be joined together. Unlike the joining method used for a treatment container of a water-conducting household appliance, however, the holding elements are not located on the side which is protected against moisture.
Various connection technologies using a separate holding element to join together two mechanically separate components are also known from DE 812 130. None of the connection technologies presented and described in the figures are, however, suitable for use in water-conducting household appliances.
From JP 08155564 a method is also known for joining together two metallic components in which the mechanical connection is made by means of laser welding. Furthermore, a seal element is provided in a section of the connection which is different from the welded area.
In JP 2002239755 A a watertight connection is proposed by intermeshing folded-over edge sections of two components. Because no separate seal element is provided, however, the connection shown would be susceptible to crevice corrosion if used in a water-conducting household appliance.